m4_comment([$Id: mempfile_class.so,v 10.24 2004/08/13 03:38:58 bostic Exp $])

define(M4PAGELOCAL, DbMpoolFile)
include(m4/m4.seealso)

m4_pf_header(m4_ref(DbMpoolFile),
ifelse(M4API, C_API, [dnl
typedef struct __db_mpoolfile DB_MPOOLFILE;
])
ifelse(M4API, CXX_API, [dnl
class DbMpoolFile {
public:
	DB_MPOOLFILE *DbMpoolFile::get_DB_MPOOLFILE();
	const DB_MPOOLFILE *DbMpoolFile::get_const_DB_MPOOLFILE() const;
	...
};
]))

m4_p([dnl
The memory pool interfaces for the m4_db database environment are
methods of the m4_ref(DbEnv) handle.  The m4_ref(DbEnv) memory pool
methods and the m4_ref(DbMpoolFile) class provide general-purpose,
page-oriented buffer management of files.  Although designed to work
with the other m4_ref(Db) classes, they are also useful for more general
purposes.  The memory pools are referred to in this document as simply
m4_italic(pools).])

m4_p([dnl
Pools may be shared between processes.  Pools are usually filled by
pages from one or more files.  Pages in the pool are replaced in LRU
(least-recently-used) order, with each new page replacing the page that
has been unused the longest.  Pages retrieved from the pool using
m4_ref(memp_fget) are m4_italic(pinned) in the pool until they are
returned to the control of the buffer pool using the m4_ref(memp_fput)
method.])

m4_p([dnl
The m4_ref(DbMpoolFile) object is the handle for a file in the memory
pool.  The handle is not free-threaded.  Once the m4_refT(memp_fclose)
is called, the handle may not be accessed again, regardless of that
method's return.])

ifelse(M4API, CXX_API, [dnl
m4_p([dnl
Each m4_ref(DbMpoolFile) object has an associated m4_refc(DbMpoolFile)
structure, which is used by the underlying implementation of m4_db and
its C-language API.  The DbMpoolFile::get_DB_MPOOLFILE method returns a
pointer to this struct.  Given a const m4_ref(DbMpoolFile) object,
DbMpoolFile::get_const_DB_MPOOLFILE returns a const pointer to the same
struct.])

m4_p([dnl
These methods may be useful for m4_db applications including both C
and C++ language software.  It should not be necessary to use these
calls in a purely C++ application.])])

m4_seealso(DbMpool)
m4_page_footer